"Concentrating power in fewer hands is risky," said Julian Evans-Pritchard, a China economist at Capital Economics. He says other top officials will be less likely to push back against a more powerful Xi, even if the president's plans could harm the economy.

Xi and other top officials have talked about reducing risks in the financial system. But analysts say the government hasn't yet taken real steps to cut debt, which could do serious damage to the economy if left unchecked.

Moody's and S&P angered China last year by downgrading its credit rating and warning about debt.

Alex Wolf, an economist at Aberdeen Standard Investments in Hong Kong, says Xi may not be the right man to push China's economy "to the next level."

He points out that propping up growth will only get harder as China's population ages and its workforce shrinks.

Under Xi, China hasn't done enough to promote innovation or protect intellectual property, while the government is still too eager to direct investment to the wrong places and reluctant to embrace free markets, according to Wolf.

"China's future rests on the shoulders of one man," he said. "Long term, that creates a lot of questions."

Potential upside

But some experts argue that extending Xi's period in office could help him to step up efforts to address the economic problems China faces, and lead to greater continuity in policy.

"I think it can be positive for reforms given that Xi has more time," said Aidan Yao, an economist at Axa Investment Managers in Hong Kong.